Fuel system for internal combustion engine

ABSTRACT

A fuel processing unit replacing the usual carburetor provides passage means maintained at sub-atmospheric pressure through which an airstream flows from an air-intake port of the unit to intake manifold of the engine. A heating coil wound helically to a cylindrical configuration is embraced by a cylindrical fine mesh wire screen which is heated by the heating coil and is continuously sprayed from the outside with volatile liquid fuel. The airstream that flows through the passage means flows radially inwardly through the cylindrical screen and through the closely spaced turns of the helical heating coil to produce a completely dry gaseous stream of air and fuel vapor which is then subjected to turbulence to result in a uniform mixture. When the engine is started while cold a thermostatic valve feeds liquid fuel into the air-vapor stream, and when a throttle valve is opened to accelerate the engine, additional air is fed into the turbulent zone of the fuel mixture stream.

1 Mar. 18, 1975 1 FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINE [76]Inventor: Jake J. Walcker, 286 Merrywood Cir., Lorna, Calif. 91752 [22]Filed: Nov. 8, 1973 [21] Appl. N0.: 413,955

[52] US. Cl 261/145, 261/154, 261/79 R, 261/39 D, 261/105, 26l/DIG. 6,123/122 R,

[51] Int. Cl. F02m 15/02 [58] Field of Search 261/145, 105, 106, 153,

261/154, 144, 79 R, 39 D, DIG. 6, 36 A; 123/135, 122 R; 55/240 FOREIGNPATENTS OR APPLICATIONS 874,081 4/1942 France 261/105 102,574 1l/1937Australia 2.61/145 1,257,832 2/1961 France 261/79 R Primary Examiner-TimR. Miles Attorney, Agent, or FirmHerbert E. Kidder [57] ABSTRACT A fuelprocessing unit replacing the usual carburetor provides passage meansmaintained at subatmospheric pressure through which an airstream flowsfrom an air-intake port of the unit to intake manifold of the engine. Aheating coil wound helically to a cylindrical configuration is embracedby a cylindrical fine mesh wire screen which is heated by the heatingcoil and is continuously sprayed from the outside with volatile liquidfuel. The airstream that flows through the passage means flows radiallyinwardly through the cylindrical screen and through the closely spacedturns of the helical heating coil to produce a completely dry gaseousstream of air and fuel vapor which is then subjected to turbulence toresult in a uniform mixture. When the engine is started while cold athermostatic valve feeds liquid fuel into the airvapor stream, and whena throttle valve is opened to accelerate the engine, additional air isfed into the turbulent zone of the fuel mixture stream.

4 Claims, 8 Drawing Figures 1" MENTEU MAR I 8 i975 sum 3 9 3 FUEL SYSTEMFOR INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION Carburetorsystems for internal combustion engines have been developed to a highlyadvanced state by decades of intensive engineering but, nevertheless,prevalent types of carburetors inherently operate to produce mixtures ofair and fine fuel mist or minute droplets of liquid fuel. The fact thatthe combustion of a fine droplet of liquid fuel is progressive, startingat the surface of the droplet, has two results, namely, incompletecombustion of the liquid fuel and attenuation of the combustion.

It is well known that incomplete combustion produces exhaust gases thatcontain excessive unburnt hydrocarbons and excessive carbon monoxide topollute the atmosphere. It is also well known that incomplete combustioncauses deposits of carbon on interior engine surfaces. It is furtherwell known that attenuation of the combustion period requires that theignition be substantially advanced to provide peak combustion pressurein each cylinder when the piston in the cylinder reaches the top of itscompression stroke.

In contrast, it is well known that a purely gaseous fuel mixture such asproduced by propane fuel burns cleanly with minimum pollution and burnsso rapidly that ignition may be set to occur at or close to the top ofthe compression stroke.

Considerable development work has been undertaken to modifycarburetor-equipped engines to lower the production of pollutants bymore complete combustion of the fuel. I have found that a more promisingapproach. however. is to avoid a conventional carburetor system and touse, instead, a fuel system that employs liquid fuel, but in doing' soproduces a completely dry, uniform, gaseous mixture of air and fuelvapor.

SUMMARY or THE INVENTION The primary object of this invention is toprovide a fuel system in the form of a compact fuel processing unit forattachment to the intake manifold of an inter nal combustion engine,wherein conventional liquid hydrocarbon fuel, such as gasoline, isemployed to produce a completely dry and uniform gaseous mixture of airand fuel vapor for complete, clean and rapid combustion on the powerstroke of each cylinder. Such a fuel system inherently results inincreased horsepower, greater engine efficiency, substantially moremileage per gallon of fuel, better engine operation at lower operatingtemperatures and striking reduction of pollutants in the engine exhuast.Unburned hydrocarbons are practically nil and the production of carbonmonoxide is drastically reduced.

Briefly described, the object of the invention is attained by sprayingvolatile liquid fuel onto a cylindrical, fine mesh screen that is heatedby a contiguous heating coil. The airstream created by the engine intakeis swirled against the outer circumference of the screen to flowradially inwardly through the screen into intimate contact with the hotsurfaces of the turns of the heater coil to result in completevaporization of the fuel that is picked up by the airstream. Thevapor-laden airstream is then passed through a turbulence zone forconversion into a completely uniform gaseous mixture of air and fuelvapor. For cold start of the engine, liquid fuel is introduced into theair-fuel stream and when the engine is accelerated by opening thethrottle valve, additional air is introduced into the turbulence zone ofthe airstream.

These and other objects and advantages of the fuel system may beunderstood by the following detailed description of the preferred formof my invention, taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the presentlypreferred embodiment of the fuel processing unit;

FIG. 2 is a side elevation of the unit;

FIG. 3 is a horizontal section as indicated by the line 3 3 of FIG. 2;

FIG. 4 is a sectional view taken as indicated by the angular line 4-4 ofFIG. 1;

FIG. 5 is an enlarged fragmentary sectional view, showing theconstruction of an axial chamber in the center of the unit;

FIG. 6 is an enlarged plan view of the top ofthe axial chamber, as seenalong line 66 of FIG. 2;

FIG. 7 is a fragmentary sectional view taken along line 7-7 of FIG. 6,showing the construction of a relief valve at the top of the axialchamber; and

FIG. 8 is a fragmentary sectional view taken along line 8-8 of FIG. 1,showing mechanism controlled by the throttle linkage for introducingadditional air into the axial chamber when the throttle valve is open toaccelerate the engine.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawings show a fuelprocessing unit. designated in its entirety by the reference numeral 10,which in corporates the fuel system of the present invention. Unit 10has a cylindrical casing 12 with a top wall 14, an outer cylindricalwall 15 formed with a conical lower portion 16, and a bottom wall 18,which may be attached by screws 20 to an intake manifold 22 of aninternal combustion engine. The bottom wall 18 has a circular opening 24for direct communication with the intake manifold. The casing 12 has aninternal, upstanding cylindrical flange 25 which together with the lowerconical portion 16 of the outer cylindrical wall 15 forms an annularreceptacle to collect residual liquid fuel, designated 26, forappropriate disposal. In this instance the annular receptacle isprovided with a drainage nipple 28 which is connected to a return hose30 for recycling of the collected residual liquid fuel.

The outer cylindrical wall 15 of the casing, together with thecylindrical wall 32 of the upright axial chamber 34 in the casing, formsan annular processing cham ber 35, and an upright cylindrical cage 36 ofopen construction divides the annular processing chamber into an outerannular compartment 38 and an inner annular compartment 40.

Unit 10 forms a passage means for air flow therethrough to the intakemanifold 22, and, in effect, the passage means is enlarged to form theannular processing chamber 35. From the inner annular compartment 40 ofthe annular processing chamber, the passage means is continued by theinterior of the axial chamber 34, the lower portion of the cylindricalwall 32 of the axial chamber being provided with a plurality of verticaland circumferentially distributed apertures 42 to admit the gaseousfluid. The lower end of the axial chamber continues the passage means tothe intake manifold 22.

The passage means through the unit has a cylindrical intake port 44which is positioned tangentially of the outer, annular compartment 38 ofthe processing chamber, to cause the incoming airstream to swirl aroundthe entire circumference of the cage 36.

Air flow into the intake port 44 is controlled by a butterfly valve 45which is mounted eccentrically, i.e., offcenter, on an upright valvestem 46 that extends through the top wall 14 of the casing. Valve stem46 is provided on its outer end with a radial arm 48 connected to atension spring 50 that biases the butterfly valve 45 towards its closedposition. The off-center location of the valve stem 46 dividesthebutterfly valve into a major wing 52 and a minor wing 54 ofsubstantially smaller area than the major wing. It is apparent thatbecause of the difference in area of the two wings 52 and 54, butterflyvalve 45 functions as a normally closed check valve which opens when apredetermined pressure differential exists across the butterfly valve.Under normal operating conditions, the butterfly valve 45 functions tomaintain sub-atmospheric pressure inside the casing 12, with themagnitude of the subatmospheric pressure determined by the tensionspring 50.

The cylindrical cage 36 supports and is embraced by a heating coil 55that is helically wound to cylindrical configuration. Heating coil 55 isin the form of a tube through which circulates a suitable heated fluid,such as hot water from the radiator, or hot exhaust gases from theengine, and for this purpose the heating tube has an upwardly extendingintake end 56, shown in FIGS. 2 and 4, and an outlet end 58 shown inFIG. 2.

The heating coil 55 heats a cylindrical, fine mesh wire screen 60 whichsnugly embraces the heating coil and which is continuously wetted bysuitably supplied volatile liquid hydrocarbon fuel, such as conventionalgasoline. Liquid fuel may be supplied to the wire screen 60 by a fuelmanifold in the form of a circular tube 62 that has numerous spacedsmall apertures to direct liquid jets 64 onto the wire screen.

The arrangement for supplying liquid fuel to the circular tube 62 isbest shown in FIGS. 1 and 2, where a supply tube 65 from a suitableelectric fuel pump (not shown) is connected to a pressure regulator 66,which reduces the pressure of the liquid to approximately 1 psi. Theliquid fuel at reduced pressure flows from the pressure regulator 66through a short hose 68 to one arm of a T-fitting 70. The stem 72 of theT-fltting 70 is connected by a short tube 74 to a T-fitting 75, shown inFIG. 3, that is incorporated in the circular fuel tube 62.

The second arm of the T-fitting 70 is connected by a short tube 76 to athermostatic valve 78 of wellknown construction, which supplies liquidfuel to a choke tube 80 that terminates at an inlet port 82 (FIG. in theupper end of axial chamber 34. The thermostatic valve 78 is responsiveto the temperature of the engine, and for this purpose a tube 84 maysupply the thermostatic valve with either hot gases from the engineexhaust or hot water from the cooling system of the engine.

The axial chamber 34 extends upward through the upper end wall 14 of thecasing 12 and has a relatively thick upper end wall 85 through which anaxial tube 86 extends to the bottom region of the axial chamber tosupply additional air thereto when the throttle valve of the engine isopened for acceleration of the engine. As best shown in FIG. 5, theupper exterior end of the axial tube 86 has a radial inlet port 88 andis embraced by a collar 90 into which a nipple fitting 92 is screwed inalignment with the inlet port. The nipple fitting 92 is connected by ahose 94 to the intake filter (not shown) of the engine to receive cleanair therefrom. The bottom of the axial tube 86 is closed, but the lowerportion of the axial tube is provided with a plurality of longitudinalslots 95 for discharging the additional air therefrom into the lowerportion of the axial chamber 34.

Slidingly mounted in the upper open end of the axial tube 86 is a sleevevalve 96 that has a radial port 98 of substantially greater verticaldimension than the inlet port 88 in the axial tube. The lower end ofsleeve valve 96 is formed with a pair of diametrically opposite endslots 100 that straddle a fixed diametrical pin 102 to prevent rotationof the sleeve valve, and thereby keep the inlet port 98 of the sleevevalve in alignment with the inlet port 88 of the axial sleeve 86. Asuitable coiled compression spring 104 inside the sleeve valve 96 actsunder compression between the diametrical pin 102 and the upper end wall105 of the sleeve valve to urge the sleeve valve upwardly towards anormal upper limit position, at which the upper end of the sleeve valveabuts an overhanging arm ofa control lever 106. When the throttle valveof the engine is opened for increased fuel flow to accelerate theengine, the throttle linkage of the engine actuates the lever 106 todepress the sleeve valve 96, causing the inner port 98 of the sleevevalve to register with the inlet port 88 of the axial tube 86, to admitthe desired additional air into the axial tube.

As best shown in FIG. 8, control level 106 is pivotally mounted on anangular rod 108 that is rigidly mounted on a bracket 110, the bracketbeing fixed to the top wall 14 of the casing 12. In the constructionshown in FIG. 8, a threaded end portion of the angular rod 108 extendsthrough a bore 112 of the bracket and is equipped with a pair'of nuts114 that are normally tightened against opposite sides of the bracket.

Referring to FIGS. 1 and 2, the throttle linkage of the engine includesa shaft 115 having an operating arm 116, which shaft is journaled in apair of spaced arms 118 of bracket 110. FIG. 88 shows how a short arm120 on shaft 115 extends under one end of lever 106 to rock the levercounterclockwise when the engine is accelerated, thereby to depress thesleeve valve 96 to admit additional air into axial chamber 34 of theunit.

As heretofore stated, the throttle valve that controls the speed of theengine may be a conventional throttle valve in the intake manifold ofthe engine, but a feature of the present invention is that such athrottle valve is incorporated in the unit 10. The throttle valve is inthe form of a sleeve 122 which, as shown in FIGS. 4 and 5, Slidinglyembraces the axial chamber 34 in the region of the plurality ofapertures 42 in the cylindrical wall of the axial chamber. The throttlevalve 122 has a pair of diametrically opposite ears 124 which arepivotally connected to corresponding upwardly extending links 126. Eachof the links 126 is pivotally connected to a pair of short links 130that are best shown in FIG. 4, and the short links, in turn, arepivotally connected to corresponding arms 134 on the throttle linkageshaft 115. It is apparent that when throttle shaft 115 is rotatedclockwise, as viewed in FIG. 8, the clockwise rotation of the arm 120causes lever 106 to depress sleeve valve 96 to admit additional air intothe axial chamber and at the same time the two arms 134 on the throttlelinkage shaft lift the throttle valve 122 to admit additional fuel-ladenair into the engine.

Axial chamber 34 is provided with a suitable relief valve to open inresponse to any abrupt pressure rise caused by back-firing of theengine. The relief valve may be of the construction shown in FIGS. 5, 6and 7, wherein an arcuate aperture 135 in the thick upper wall 85 of theaxial chamber is of stepped configuration to form a continuous shoulder136 to support a valve member 138 in the form of a C-shaped plate. Thevalve plate 138 is retained by a pair of screws 140 which extend throughcorresponding holes 142 in its two ends. As indicated in FIG. 7, theholes 142 are oversized in relation to the screw 140 to permit the valveplate 138 to tilt up to open position in response to an abrupt pressurerise in the axial chamber. Each of the two screws 140 is provided with asuitable washer 144 that is substantially larger than the correspondinghole 142 in the valve plate.

As best shown in FIG. 5, the lower end of the axial chamber 34 isprovided with an entrance vestibule 145 which is formed by a wall 146 inthe form of a truncated cone, together with a ring-shaped wall 148 thatextends radially outwardly from the top of wall 146. The entrance to thevestibule 145 is through the previously mentioned plurality of apertures42 in the cylindrical wall 32 of the axial chamber, and the exit fromthe vestibule is through radially extending, slot-like apertures 150(see FIG. 3) in the radial wall 148. The apertures 150 are shaped anddimensioned to serve as flame-arresters, to prevent ignition of thecombustible mixture in the vestibule by back-firing of the engine.

It can be seen in FIGS. 4 and 5 that the axial tube 86 and thesurrounding upper edge of the conically shaped wall 146 form arestricted annular throat 152 which discharges into a progressivelyenlarged annular turbulence zone 154. The annular fuel-laden airstreamflowing upwardly through the radial slots 150 makes a sharp reversal ofdirection to enter the throat 152, as indicated by the curved arrows155. This sharp reversal of flow direction into the throat 152, followedby expansion in the turbulence zone 154 results in such a high degree ofturbulence that the air and dry fuel vapor intermix thoroughly toproduce a uniform mixture. When additional air is discharged through theslots 95 of the axial tube 86 into the turbulence zone 154, the new airbecomes part of the uniform mixture.

The manner in which the processing unit functions for its purpose may bereadily understood from the foregoing description. The airstream fromthe intake port 44 swirls circumferentially through the outer annularcompartment 38 to pick up fuel vapor from the liquid fuel on thecylindrical screen 60, and the cylindrical screen forms the fuel-ladenair into an exceedingly large number of minute, radially inward streamsthat are directed into intimate contact with the heated surfaces of theheating coil 55. The heat added by the surfaces of the heating coilcompletely vaporizes any fine droplets of liquid fuel that may beentrained in the minute airstreams, the consequence being that themixture that flows into the inner annular chamber 40 is a completely drygaseous mixture of air and fuel vapor. The passage of this mixturethrough vestibule 145, together with the abrupt reversal in directionthrough throat 152 into turbulence Zone 154 and the violent turbulencein the turbulence zone, insure that the final mixture that reaches theintake manifold of the engine is a completely uniform mixture. The finalmixture burns cleanly with an extremely high speed rate of combustion.In contrast, the usual carbureted mixture contains many fine droplets ofliquid fuel, some of which do not vaporize until after they have beendischarged through the exhaust valves of the engine.

The complete vaporization of the liquid fuel by the unit 10 results inbetter combustion, greater engine efficiency, and more mileage pergallon offuel. with drastic reduction in atmospheric pollution, nounburned liquid fuel whatsoever being discharged into the atmosphere.

It has been found that ignition of the completely gas eous fuel may beadvantageously retarded 35 from standard specification because of thefaster rate of combustion of the uniform, dry, gaseous vapor-airmixture, which causes the combustion pressure to reach its peak fasterthan is possible with a conventional carbu reted fuel mixture. Thus theinvention approaches the ideal of having maximum combustion pressureoccur quickly and precisely at top dead center.

It can be readily appreciated that the fuel processing unit is ofsimple, uncomplicated construction, with nothing to get out of order.The unit is easy to service. The cost of the unit is comparable to thecost of a conventional carburetor, but it accomplishes greater poweroutput than a conventional carburetor, and in fact, produces greaterpower output than natural gas or propane conversion systems with nogreater pollution of the atmosphere.

In a laboratory test, a 392-cubic-inch Cadillac engine (1962) in goodmechanical condition was run at 1,500 rpm with the exhaust systemconnected to an exhaust gas analyzer. The indicator on the analyzer forunburned hydrocarbons registered zero and the indicator for carbonmonoxide registered 0.25 percent, which is well below the stringentstandards set for automobiles to be produced in 1975.

While I have shown and described in considerable detail what I believeto be the preferred form of my invention, it will be understood by thoseskilled in the art than the invention is not limited to such details,but may take various other forms within the scope of the followingclaims.

I claim:

1. In a fuel system for an internal combustion engine having an intakemanifold, a source of liquid hydrocarbon fuel, a source of heated fluid,and a throttle linkage, the combination of:

a generally circular housing mounted on the end of said intake manifoldand having an inlet opening through one wall thereof;

a cylindrical conduit disposed vertically within said housing at thecenter thereof, the bottom end of said conduit being attached to thebottom of the housing and communicating with the interior of said intakemanifold;

21 length of heat-exchange tubing wound into a vertically disposedcylindrical coil surrounding said conduit, the individual turns of thecoil being closely spaced apart with respect to one another;

the ends of said heat exchange tubing being connected to said source ofheated fluid, whereby the heated fluid is circulated continuouslythrough the tubing;

a wire mesh screen wrapped around said coil of heat exchange tubing inclose, heat-exchange contact therewith, whereby the screen becomes hotby conduction of heat from the tubing;

means for flowing liquid hydrocarbon fuel down over said wire meshscreen from the top edge thereof;

the liquid fuel flowing down over said hot wire mesh screen and thecoils of heated tubing being vaporized, and the fuel vapor being mixedwith air flowing radially inward through the screen;

means for admitting the mixture of vaporized fuel and air into saidconduit;

means connected to said throttle linkage for controlling the volume ofvaporized fuel and air mixture into said intake manifold; and

means for introducing a controlled amount of additional fresh air intosaid fuel-and-air mixture as the latter flows downwardly through saidconduit into said intake manifold.

2. The combination as set forth in claim 1, wherein said means foradmitting the mixture of vaporized fuel and air into said conduitcomprises a plurality of apertures in the wall of the conduit at thelower end thereof; said apertures opening into a vestibule formed by anupwardly converging, conical inner wall, and an annular top wall; saidannular top wall having apertures therein through which the fuel/airmixture enters said conduit, where it reverses direction and flowsdownwardly through the center opening of said conical inner wall intosaid intake manifold.

3. The combination as fet forth in claim 2, wherein said means forintroducing a controlled amount of additional fresh air into saidfuel/air mixture comprises a hollow tube extending downwardly throughsaid conduit along the axis thereof and through said center opening ofsaid conduit inner wall; said hollow tube having apertures in the bottomend thereof, below the top of said conical inner wall; and means foradmitting fresh air into said tube at the top end thereof.

4. The combination as set forth in claim 3, wherein there/is a tubularvalve member slidably disposed within said hollow tube; said valvemember cooperating with an aperture in the wall of the hollow tube tocontrol the flow of air into the hollow tube; spring means urging saidvalve member in one direction; and actuating means connected to saidthrottle linkage for moving said valve member in the other directionagainst the resistance of said spring means.

* l l= l

1. In a fuel system for an internal combustion engine having an intakemanifold, a source of liquid hydrocarbon fuel, a source of heated fluid,and a throttle linkage, the combination of: a generally circular housingmounted on the end of said intake manifold and having an inlet openingthrough one wall thereof; a cylindrical conduit disposed verticallywithin said housing at the center thereof, the bottom end of saidconduit being attached to the bottom of the housing and communicatingwith the interior of said intake manifold; a length of heat-exchangetubing wound into a vertically disposed cylindrical coil surroundingsaid conduit, the individual turns of the coil being closely spacedapart with respect to one another; the ends of said heat exchange tubingbeing connected to said source of heated fluid, whereby the heated fluidis circulated continuously through the tubing; a wire mesh screenwrapped around said coil of heat exchange tubing in close, heat-exchangecontact therewith, whereby the screen becomes hot by conduction of heatfrom the tubing; means for flowing liquid hydrocarbon fuel down oversaid wire mesh screen from the top edge thereof; the liquid fuel flowingdown over said hot wire mesh screen and the coils of heated tubing beingvaporized, and the fuel vapor being mixed with air flowing radiallyinward through the screen; means for admitting the mixture of vaporizedfuel and air into said conduit; means connected to said throttle linkagefor controlling the volume of vaporized fuel and air mixture into saidintake manifold; and means for introducing a controlled amount ofadditional fresh air into said fuel-and-air mixture as the latter flowsdownwardly through said conduit into said intake manifold.
 2. Thecombination as set forth in claim 1, wherein said means for admittingthe mixture of vaporized fuel and air into said conduit comprises aplurality of apertures in the wall of the conduit at the lower endthereof; said apertures opening into a vestibule formed by an upwardlyconverging, conical inner wall, and an annular top wall; said annulartop wall having apertures therein through which the fuel/air mixtureenters said conduit, where it reverses direction and flows downwardlythrough the center opening of said conical inner wall into said intakemanifold.
 3. The combination as fet forth in claim 2, wherein said meansfor introducing a controlled amount of additional fresh air into saidfuel/air mixture comprises a hollow tube extending downwardly throughsaid conduit alonG the axis thereof and through said center opening ofsaid conduit inner wall; said hollow tube having apertures in the bottomend thereof, below the top of said conical inner wall; and means foradmitting fresh air into said tube at the top end thereof.
 4. Thecombination as set forth in claim 3, wherein there/is a tubular valvemember slidably disposed within said hollow tube; said valve membercooperating with an aperture in the wall of the hollow tube to controlthe flow of air into the hollow tube; spring means urging said valvemember in one direction; and actuating means connected to said throttlelinkage for moving said valve member in the other direction against theresistance of said spring means.